A socket which puts contact portions of socket-side contacts exposed in an accommodation recess into contact with plug-side contacts exposed in one surface of a counterpart plug connection portion accommodated in the accommodation recess to establish electrical connection with the plug connection portion may be expected to be used in an inferior environment. Examples of the inferior environment include outdoors where the socket is exposed to dust and the weather, and bathrooms and kitchens where the socket is exposed to water droplets and dust. There has been known a socket that hermetically seals a contact space in which the plug-side contacts and the socket-side contacts are in contact with each other from outside so that water droplets, dust, or the like may not get into the contact space to cause poor contact and the like (Patent Literature 1).
Such a socket 100 described in Patent Literature 1, which hermetically seals the contact space from outside, will be described below with reference to FIGS. 24A, 24B, and 25. The socket 100 includes an insulating housing 101 and a plurality of socket-side contacts 102, 102, . . . which are insulated from each other and fixed to the insulating housing 101. The insulating housing 101 includes a housing main body 101a, a tongue piece 101b, and a partition plate 101c. The housing main body 101a has a rectangular cylindrical shape. The partition plate 101c partitions a rectangular cylindrical hole of the rectangular cylindrical housing main body 101a. The tongue piece 101b is horizontally protruded forward from the partition plate 101c toward a counterpart plug connection portion inserted.
Each socket-side contact 102 is integrally insert-molded to run through the partition plate 101c when the tongue piece 101b and the partition plate 101c are integrally molded of an insulating synthetic resin. A contact portion 102a at one end side is exposed in a flat surface side of the tongue piece 101b. A leg portion 102c to be soldered to a pattern of a printed wiring board is protruded in a crank shape from the bottom side of the partition plate 101c and fixed to the housing 101.
The outline of the rectangular partition plate 101c is configured to fit to the rectangular cylindrical hole of the housing main body 101a. A locking protrusion 103 protruded from a flat surface of the partition plate 101c is locked to a locking hole 104 formed in a rear portion of a flat surface of the housing main body 101a, whereby the partition plate 101c is fixed to the housing main body 101a to cover an opening in the rear of the housing main body 101a. As shown in FIGS. 24A and 24B, an 0 ring 105 is arranged around the entire outer periphery of the rectangular partition plate 101c. The 0 ring 105 is in close contact with and interposed between the inner wall surface of the rectangular cylindrical hole of the housing main body 101a and the partitioning plate 101c fixed inside. The housing main body 101a and the outer periphery of the partition plate 101c are thereby hermetically sealed without a gap.
The partition plate 101c covers the opening in the rear of the rectangular cylindrical hole of the housing main body 101a, whereby an accommodation recess 106 for inserting and accommodating the counterpart plug connection portion into the insulating housing 101 from the front is formed as shown in FIG. 25. The tongue piece 101b with the contact portions 102a of the socket-side contacts 102 located in its flat surface protrudes into the accommodation recess 106 along a horizontal plane.
The accommodation recess 106 in which the contact portions 102a of the socket-side contacts 102 are located is hermetically sealed from outside without a gap, except a front opening 106a. With the counterpart plug connection portion inserted from the opening 106a and accommodated in the accommodation recess 106, the contact space in which the plug-side contacts (not shown) of the plug connection portion and the contact portions 102a of the socket-side contacts 102 are in contact with each other is thus hermetically sealed from outside, and water droplets or dust will not get into the contact space.
However, if a plug connection portion having no gap around is attempted to be inserted into the completely-sealed accommodation recess 106, the air inside the accommodation recess 106 is not let out and produces high internal pressure which interferes with the insertion of the plug connection portion. A gap therefore needs to be formed to let the air out of the accommodation recess 106 when the plug connection portion is inserted. A socket described in Patent Literature 2 includes a seal member that is interposed to cover a gap between the outer peripheral surface of the plug connection portion and the inner wall surface of the accommodation recess when the plug connection portion is inserted deepest into the accommodation recess, whereby the contact space is hermetically sealed.